1. Field of the Invention
The invention relates to a method for producing a three-dimensional structure in a lithographic material.
Such lithographic methods are used, for example, when producing prototypes or workpieces with special shape requirements. In particular, such methods are used to produce micro or nanostructures, e.g. For experimental purposes and in areas in which great freedom of design is desired. Applications include, for example, the production of moldable topographies, templates, or dies for mass replication, the production of light guides, and the production of fitted prostheses for medical applications.
2. Description of Related Art
Among the known methods are various methods of so-called stereolithography (e.g. from U.S. Pat. No. 4,575,330 A1), wherein the desired structure is built up in layers in a bath of fluid lithographic materials, in particular photopolymer, by targeted exposure to a writing beam. The writing beam polymerizes a film at the surface of the bath of lithographic material into a desired pattern by local exposure. The structure is built up in layers by gradually lowering the substrate into the bath of lithographic material. It is also known (e.g. from DE 195 07 881 B4) that the layered structure can be provided with additional support structures, which are also produced in the lithographic material and typically extend outside the structure to support the structure on the substrate. Such support structures prevent a collapse of the unfinished structure.